1. Field of the Invention
The present invention relates to a class D electroacoustic amplifier, i.e. a class D audio amplifier, and a method for compensation of power supply voltage influence on an output audio signal in the class D audio amplifier.
2. Brief Description of the Background of the Invention Including Prior Art
One of the features of class D electroacoustic amplifiers is making use of a carrier signal apart from the audio signal. One of these amplifiers is the one known from the U.S. Pat. No. 4,182,992, which consists of, among others, two transistors and a diode.
In turn, from the U.S. Pat. No. 4,178,556 there is known a class D amplifying circuit that contains a modulating circuit to modulate an audio signal and a carrier signal.
There is also known, from the U.S. Pat. No. 6,300,825 an amplifier that makes use of pulse width modulation of a signal, containing a comparator and an integrating circuit, which in order to increase the coefficient of rejection of supply voltage fluctuations, was supplemented with another integrating circuit.
From the Polish patent description P-325207 there is known a circuit for compensation of the constant component of the output voltage, powered by a stabilised voltage that generates a voltage compensation signal. This signal is added in an adder to a voltage signal of a triangular wave generator and in this way it changes the constant component of the output signal of the generator. The changed constant component influences the value of the duty cycle coefficient of the rectangular impulses generated at the output of the comparator, compensating to a degree the supply voltage fluctuations.